Inorganic molten salts are known as fluxes for the synthesis of novel bulk inorganic compounds and of mesostructures and nanostructures with crystal habits different from those observed in more conventional solvents. However, they have not demonstrated the ability to provide mesostructures and nanostructures of complex metal oxides that are currently unreported at the mesoscale and nanoscale. In this report, we show the first occurrence of Sr₄Mn₃O₁₀ at the mesoscale, as platelets synthesized in molten strontium hydroxide at 600 °C with basal faces of few hundreds of nanometers and thicknesses ranging from 20 to 100 nm. We address carefully the atom-scale structure by transmission electron microscopy, including electron energy loss spectroscopy and electron tomography. We then propose that the final morphology is driven by the surface charge of each facet through surface energy. The reactivity of these platelets is then addressed, highlighting cation leaching when in contact with acidic water, which results in crystalline–amorphous core–shell platelets that are active electrocatalysts towards the oxygen reduction reaction.

中文翻译：

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多阳离子Sr ₄ Mn ₃ O ₁₀介观结构：熔盐合成，分析电子显微镜研究和反应性†

无机熔融盐被称为助熔剂，用于合成新型块状无机化合物以及介晶结构和纳米结构，其晶体习性不同于在常规溶剂中观察到的那些。但是，他们尚未证明能够提供目前在中尺度和纳米尺度上尚未报道的复杂金属氧化物的中观结构和纳米结构。在此报告中，我们显示了Sr ₄ Mn ₃ O ₁₀的首次出现在中尺度上，血小板是在600°C的熔融氢氧化锶中合成的，其基面为几百纳米，厚度为20至100 nm。我们通过透射电子显微镜，包括电子能量损失谱和电子断层扫描，仔细研究了原子尺度的结构。然后，我们提出最终的形态是由每个小面的表面电荷通过表面能驱动的。然后解决了这些血小板的反应性，突出了与酸性水接触时阳离子的浸出，这导致了结晶-无定形的核-壳血小板，这是氧还原反应的活性电催化剂。